A 7,000-year-old monument dubbed the “Spanish Stonehenge” has been exposed for the first time in 50 years, after drought conditions in western Spain dropped water levels in a man-made lake and revealed the ancient standing stones.

The circle of more than 100 large rocks, known as the Dolmen of Guadalperal, was submerged in 1963 after the Spanish government constructed the Valdecañas Reservoir to feed a hydroelectric dam that still generates power in the region. Occasionally, the tips of the tallest standing stones have been visible as the reservoir’s water levels have changed, but according to NASA, this is the first time that the entire monument has been out of water since the area was flooded to create the lake.

Water levels in the reservoir dropped significantly this summer after two intense heat waves baked much of Europe. In Spain, June’s hot spell saw seven weather stations record their highest temperatures ever, according to the country’s meteorological agency, with several cities exceeding 104 degrees Fahrenheit (40 degrees Celsius). Higher-than-average temperatures and dry conditions were also recorded across Spain in July and August.

NASA’s Landsat 8 satellite snapped pictures of the area July 25. In a comparison of satellite views taken of the same area in 2013, it’s possible to see the changing coastlines around the Valdecañas Reservoir and more pronounced vein-like features in the water that represent the exposed lake bottom.

A comparison of satellite views from July 24, 2013 and July 25, 2019 show changes to the coastlines around the Valdeca?as Reservoir.earthobservatory.nasa.gov

“Raising and lowering of the water level is destructive, but it can be revealing too,” Craig Lee, an environmental archaeologist at the University of Colorado, Boulder, said. “It can sometimes expose sites in remarkable ways.”

The Dolmen of Guadalperal was excavated in the 1920s by a German archaeologist named Hugo Obermaier, but his findings were not published until the 1960s, after the Valdecañas Reservoir was constructed and the monument was flooded.

Archaeologists think the standing rocks may have been part of an enclosed structure with an enormous stone cap, and was possibly used as a tomb, a site for trade or a space for religious rituals.

Lee said discoveries like the Dolmen of Guadalperal demonstrate how droughts and other extreme conditions exacerbated by climate change can sometimes be a boon for archaeology — what he called “a silver lining.” But, in many other cases, climate change is having the opposite effect, such as threatening existing archaeological sites.

“It’s forcing our hand,” Lee said. “With climate change, it’s like playing chess against someone who is just slaughtering your pawns and other higher pieces — you have to just engage and play because you don’t have a chance to think about a sophisticated level of strategy.”